Re: [PATCH v9 2/3] x86, apicv: add virtual x2apic support

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On Fri, Jan 11, 2013 at 02:37:15AM +0000, Zhang, Yang Z wrote:
> Gleb Natapov wrote on 2013-01-10:
> > On Thu, Jan 10, 2013 at 08:32:06AM +0000, Zhang, Yang Z wrote:
> >> Gleb Natapov wrote on 2013-01-10:
> >>> On Thu, Jan 10, 2013 at 03:26:07PM +0800, Yang Zhang wrote:
> >>>> From: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> >>>> 
> >>>> basically to benefit from apicv, we need to enable virtualized x2apic mode.
> >>>> Currently, we only enable it when guest is really using x2apic.
> >>>> 
> >>>> Also, clear MSR bitmap for corresponding x2apic MSRs when guest enabled
> >>> x2apic:
> >>>>     0x800 - 0x8ff: no read intercept for apicv register virtualization,
> >>>>     		   except APIC ID and TMCCT.
> >>>>     APIC ID and TMCCT: need software's assistance to get right value.
> >>>>     TPR,EOI,SELF-IPI: no write intercept for virtual interrupt delivery.
> >>>> Signed-off-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> >>>> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> >>>> ---
> >>>>  arch/x86/include/asm/kvm_host.h |    2 + arch/x86/include/asm/vmx.h
> >>>>    |    1 + arch/x86/kvm/lapic.c            |    5 +-
> >>>>    arch/x86/kvm/svm.c              |    6 + arch/x86/kvm/vmx.c |  194
> >>>>    +++++++++++++++++++++++++++++++++++++-- 5 files
> > changed, 200
> >>>>  insertions(+), 8 deletions(-)
> >>>> diff --git a/arch/x86/include/asm/kvm_host.h
> >>>> b/arch/x86/include/asm/kvm_host.h index c431b33..572a562 100644 ---
> >>>> a/arch/x86/include/asm/kvm_host.h +++
> >>>> b/arch/x86/include/asm/kvm_host.h @@ -697,6 +697,8 @@ struct
> >>>> kvm_x86_ops {
> >>>>  	void (*enable_nmi_window)(struct kvm_vcpu *vcpu);
> >>>>  	void (*enable_irq_window)(struct kvm_vcpu *vcpu);
> >>>>  	void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);
> >>>> +	void (*enable_virtual_x2apic_mode)(struct kvm_vcpu *vcpu);
> >>>> +	void (*disable_virtual_x2apic_mode)(struct kvm_vcpu *vcpu);
> >>> Make one callback with enable/disable parameter. And do not forget SVM.
> >>> 
> >>>>  	int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
> >>>>  	int (*get_tdp_level)(void);
> >>>>  	u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool
> > is_mmio);
> >>>> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> >>>> index 44c3f7e..0a54df0 100644
> >>>> --- a/arch/x86/include/asm/vmx.h
> >>>> +++ b/arch/x86/include/asm/vmx.h
> >>>> @@ -139,6 +139,7 @@
> >>>>  #define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001 #define
> >>>>  SECONDARY_EXEC_ENABLE_EPT               0x00000002 #define
> >>>>  SECONDARY_EXEC_RDTSCP			0x00000008 +#define
> >>>>  SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE   0x00000010 #define
> >>>>  SECONDARY_EXEC_ENABLE_VPID              0x00000020 #define
> >>>>  SECONDARY_EXEC_WBINVD_EXITING		0x00000040 #define
> >>>>  SECONDARY_EXEC_UNRESTRICTED_GUEST	0x00000080
> >>>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> >>>> index 0664c13..ec38906 100644
> >>>> --- a/arch/x86/kvm/lapic.c
> >>>> +++ b/arch/x86/kvm/lapic.c
> >>>> @@ -1328,7 +1328,10 @@ void kvm_lapic_set_base(struct kvm_vcpu
> > *vcpu,
> >>> u64 value)
> >>>>  		u32 id = kvm_apic_id(apic);
> >>>>  		u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
> >>>>  		kvm_apic_set_ldr(apic, ldr);
> >>>> -	}
> >>>> +		kvm_x86_ops->enable_virtual_x2apic_mode(vcpu);
> >>>> +	} else
> >>>> +		kvm_x86_ops->disable_virtual_x2apic_mode(vcpu);
> >>>> +
> >>> You just broke SVM.
> >>>>  	apic->base_address = apic->vcpu->arch.apic_base &
> >>>>  			     MSR_IA32_APICBASE_BASE;
> >>>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> >>>> index d29d3cd..0b82cb1 100644
> >>>> --- a/arch/x86/kvm/svm.c
> >>>> +++ b/arch/x86/kvm/svm.c
> >>>> @@ -3571,6 +3571,11 @@ static void update_cr8_intercept(struct
> > kvm_vcpu
> >>> *vcpu, int tpr, int irr)
> >>>>  		set_cr_intercept(svm, INTERCEPT_CR8_WRITE);
> >>>>  }
> >>>> +static void svm_enable_virtual_x2apic_mode(struct kvm_vcpu *vcpu)
> >>>> +{
> >>>> +	return;
> >>>> +}
> >>>> +
> >>>>  static int svm_nmi_allowed(struct kvm_vcpu *vcpu) { 	struct vcpu_svm
> >>>>  *svm = to_svm(vcpu); @@ -4290,6 +4295,7 @@ static struct kvm_x86_ops
> >>>>  svm_x86_ops = { 	.enable_nmi_window = enable_nmi_window,
> >>>>  	.enable_irq_window = enable_irq_window, 	.update_cr8_intercept =
> >>>>  update_cr8_intercept,
> >>>> +	.enable_virtual_x2apic_mode = svm_enable_virtual_x2apic_mode,
> >>>> 
> >>>>  	.set_tss_addr = svm_set_tss_addr,
> >>>>  	.get_tdp_level = get_npt_level,
> >>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> >>>> index 688f43f..b203ce7 100644
> >>>> --- a/arch/x86/kvm/vmx.c
> >>>> +++ b/arch/x86/kvm/vmx.c
> >>>> @@ -433,6 +433,8 @@ struct vcpu_vmx {
> >>>> 
> >>>>  	bool rdtscp_enabled;
> >>>> +	bool virtual_x2apic_enabled;
> >>>> +
> >>>>  	/* Support for a guest hypervisor (nested VMX) */
> >>>>  	struct nested_vmx nested;
> >>>>  };
> >>>> @@ -767,12 +769,23 @@ static inline bool
> >>> cpu_has_vmx_virtualize_apic_accesses(void)
> >>>>  		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
> >>>>  }
> >>>> +static inline bool cpu_has_vmx_virtualize_x2apic_mode(void)
> >>>> +{
> >>>> +	return vmcs_config.cpu_based_2nd_exec_ctrl &
> >>>> +		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
> >>>> +}
> >>>> +
> >>>>  static inline bool cpu_has_vmx_apic_register_virt(void)
> >>>>  {
> >>>>  	return vmcs_config.cpu_based_2nd_exec_ctrl &
> >>>>  		SECONDARY_EXEC_APIC_REGISTER_VIRT;
> >>>>  }
> >>>> +static inline bool cpu_has_vmx_virtual_intr_delivery(void)
> >>>> +{
> >>>> +	return false;
> >>>> +}
> >>>> +
> >>>>  static inline bool cpu_has_vmx_flexpriority(void)
> >>>>  {
> >>>>  	return cpu_has_vmx_tpr_shadow() &&
> >>>> @@ -2544,6 +2557,7 @@ static __init int setup_vmcs_config(struct
> >>> vmcs_config *vmcs_conf)
> >>>>  	if (_cpu_based_exec_control &
> >>>>  CPU_BASED_ACTIVATE_SECONDARY_CONTROLS) { 		min2 = 0; 		opt2 =
> >>>>  SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
> >>>>  +			SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
> >>>>  			SECONDARY_EXEC_WBINVD_EXITING | 	SECONDARY_EXEC_ENABLE_VPID |
> >>>>  			SECONDARY_EXEC_ENABLE_EPT | @@ -3731,7 +3745,45 @@ static void
> >>>>  free_vpid(struct vcpu_vmx *vmx) 	spin_unlock(&vmx_vpid_lock); }
> >>>> -static void __vmx_disable_intercept_for_msr(unsigned long
> >>>> *msr_bitmap, u32 msr) +#define MSR_TYPE_R	1 +#define MSR_TYPE_W	2
> >>>> +static void __vmx_disable_intercept_for_msr(unsigned long
> >>>> *msr_bitmap, + 					u32 msr, int type) +{ +	int f = sizeof(unsigned
> >>>> long); + +	if (!cpu_has_vmx_msr_bitmap()) +		return; + +	/* +	 * See
> >>>> Intel PRM Vol. 3, 20.6.9 (MSR-Bitmap Address). Early manuals +	 *
> >>>> have the write-low and read-high bitmap offsets the wrong way round.
> >>>> +	 * We can control MSRs 0x00000000-0x00001fff and
> >>>> 0xc0000000-0xc0001fff. +	 */ +	if (msr <= 0x1fff) { +		if (type &
> >>>> MSR_TYPE_R) +			/* read-low */ +			__clear_bit(msr, msr_bitmap +
> >>>> 0x000 / f); + +		if (type & MSR_TYPE_W) +			/* write-low */ +
> >>>> 	__clear_bit(msr, msr_bitmap + 0x800 / f); + +	} else if ((msr >=
> >>>> 0xc0000000) && (msr <= 0xc0001fff)) { +		msr &= 0x1fff; +		if (type &
> >>>> MSR_TYPE_R) + 	/* read-high */ +			__clear_bit(msr, msr_bitmap +
> >>>> 0x400 / f); + +		if (type & MSR_TYPE_W) +			/* write-high */ +
> >>>> 	__clear_bit(msr, msr_bitmap + 0xc00 / f); + +	} +} + +static void
> >>>> __vmx_enable_intercept_for_msr(unsigned long *msr_bitmap, + 					u32
> >>>> msr, int type)
> >>>>  {
> >>>>  	int f = sizeof(unsigned long);
> >>>> @@ -3744,20 +3796,75 @@ static void
> >>> __vmx_disable_intercept_for_msr(unsigned long *msr_bitmap, u32 msr)
> >>>>  	 * We can control MSRs 0x00000000-0x00001fff and
> >>>>  0xc0000000-0xc0001fff. 	 */ 	if (msr <= 0x1fff) {
> >>>> -		__clear_bit(msr, msr_bitmap + 0x000 / f); /* read-low */
> >>>> -		__clear_bit(msr, msr_bitmap + 0x800 / f); /* write-low */
> >>>> +		if (type & MSR_TYPE_R)
> >>>> +			/* read-low */
> >>>> +			__set_bit(msr, msr_bitmap + 0x000 / f);
> >>>> +
> >>>> +		if (type & MSR_TYPE_W)
> >>>> +			/* write-low */
> >>>> +			__set_bit(msr, msr_bitmap + 0x800 / f);
> >>>> +
> >>>>  	} else if ((msr >= 0xc0000000) && (msr <= 0xc0001fff)) {
> >>>>  		msr &= 0x1fff;
> >>>> -		__clear_bit(msr, msr_bitmap + 0x400 / f); /* read-high */
> >>>> -		__clear_bit(msr, msr_bitmap + 0xc00 / f); /* write-high */
> >>>> +		if (type & MSR_TYPE_R)
> >>>> +			/* read-high */
> >>>> +			__set_bit(msr, msr_bitmap + 0x400 / f);
> >>>> +
> >>>> +		if (type & MSR_TYPE_W)
> >>>> +			/* write-high */
> >>>> +			__set_bit(msr, msr_bitmap + 0xc00 / f);
> >>>> +
> >>>>  	} } + static void vmx_disable_intercept_for_msr(u32 msr, bool
> >>>>  longmode_only) { 	if (!longmode_only)
> >>>> -		__vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, msr);
> >>>> -	__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, msr);
> >>>> +		__vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, +						msr,
> >>>> MSR_TYPE_R | MSR_TYPE_W);
> >>>> +	__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode,
> >>>> +						msr, MSR_TYPE_R | MSR_TYPE_W); +} + +static void
> >>>> vmx_intercept_for_msr_read(u32 msr, bool longmode_only, +					bool
> >>>> set) +{ +	if (!longmode_only) { +		if (set) +
> >>>> 	__vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy, +					msr,
> >>>> MSR_TYPE_R); +		else +
> >>>> 	__vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, +					msr,
> >>>> MSR_TYPE_R); + +	} +	if (set)
> >>>> +		__vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode, +				msr,
> >>>> MSR_TYPE_R); +	else
> >>>> +		__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, +				msr,
> >>>> MSR_TYPE_R); +} + +static void vmx_intercept_for_msr_write(u32 msr,
> >>>> bool longmode_only, +					bool set) +{ +	if (!longmode_only) { +		if
> >>>> (set) + 	__vmx_enable_intercept_for_msr(vmx_msr_bitmap_legacy,
> >>>> +					msr, MSR_TYPE_W); +		else +
> >>>> 	__vmx_disable_intercept_for_msr(vmx_msr_bitmap_legacy, +					msr,
> >>>> MSR_TYPE_W); + +	} +	if (set)
> >>>> +		__vmx_enable_intercept_for_msr(vmx_msr_bitmap_longmode, +				msr,
> >>>> MSR_TYPE_W); +	else
> >>>> +		__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, +				msr,
> >>>> MSR_TYPE_W);
> >>>>  }
> >>>>  
> >>>>  /*
> >>>> @@ -3855,6 +3962,7 @@ static u32 vmx_secondary_exec_control(struct
> >>> vcpu_vmx *vmx)
> >>>>  		exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING; 	if
> >>>>  (!enable_apicv_reg_vid) 		exec_control &=
> >>>>  ~SECONDARY_EXEC_APIC_REGISTER_VIRT; +	exec_control &=
> >>>>  ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE; 	return
> > exec_control; }
> >>>> @@ -6110,6 +6218,76 @@ static void update_cr8_intercept(struct
> > kvm_vcpu
> >>> *vcpu, int tpr, int irr)
> >>>>  	vmcs_write32(TPR_THRESHOLD, irr);
> >>>>  }
> >>>> +static void vmx_enable_virtual_x2apic_mode(struct kvm_vcpu *vcpu)
> >>>> +{
> >>>> +	u32 exec_control;
> >>>> +	int msr;
> >>>> +	struct vcpu_vmx *vmx = to_vmx(vcpu);
> >>>> +
> >>>> +	if (!cpu_has_vmx_virtualize_x2apic_mode())
> >>>> +		return;
> >>>> +
> >>>> +	exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> >>>> +	/* virtualize x2apic mode relies on tpr shadow */
> >>>> +	if (!(exec_control & CPU_BASED_TPR_SHADOW))
> >>>> +		return;
> >>>> +
> >>>> +	exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> >>>> +	exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
> >>>> +	exec_control |= SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
> >>>> +	vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
> >>>> +	vmx->virtual_x2apic_enabled = true;
> >>> Why track it?
> >> With this flag, we don't need to read vmcs to check whether we enabled
> >> virtua x2apic before.
> >> 
> > Why do you care? Just disabled it regardless.
> kvm_lapic_set_base will be called when creating lapic. At that time, vcpu didn't initialized. Then read/write vmcs in vmx_disable_virtual_x2apic_mode will cause error.
> With this flag, we only disable the virtual x2apic mode if it is enabled before. 
> 
Then call vmx_enable_virtual_x2apic_mode() only when mode actually changes.
kvm_lapic_set_base() can track it like it does to MSR_IA32_APICBASE_ENABLE.

--
			Gleb.
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